Mississippi River Mud 
Missouri has an abundance of natural clay embedded in hillsides, creek beds, rivers, and cut away roadsides. My interest was first sparked on experimenting with natural clays from taking the kids down to play in the creek to cool off on a hot summer day. I was a newbie in my clay habit and was thrilled to find a light gray strip of pure clay embedded in the hillside and creek bottom free for the taking. Much to my husbands dismay we filled several 5 gallon buckets to take home. (The car was parked a little down the way) This led to looking at other creek beds around the property where a bright red clay was found and to firing local found"dirt dauber" nest made from nearby clay and on to the mighty Mississippi Riverbanks.
Mississippi River mud is found naturally in my area as a dark blackish sticky mud. It is called by some unhappy farmers and hunters, who have found their trucks and equipment stuck in it as, "Gumbo" mud. I have come to respect it as thousands of years of glacier action, fish, and other orgainic decomposing process. Unfortunately, it also has a monster living in it that I have not been able to completely eliminate. It has very tiny deposits of lime in it that are hard to filter out when cleaned. I found out the hard way that when lime is in the clay when fired it is altered to calcium carbonate to calcium oxide. Calcium oxide is an unstable oxide in the atmosphere because it takes on water or hydrates. This hydration which will occur slowly even in a small lump of limestone buried in a fired clay object causing the lime to swell. The swelling exerts an irresistble pressure against the fired clay that surrounds the bit of lime and will break or flake a piece of the clay off...especially in rainy, humid Missouri weather!!!!! However, I continue to try. Below is my method of "mining" my own clay.
The process of preparing natural clay is not for the impatient. I am not an expert on the chemistry of making clay but my method has worked for me.
1. First you dig it and haul it home in very heavy buckets (with a strong assistant.)
2. Lay it out on tarps to completely dry for several days (keeping the cats out of it as a litter box.)
3 Next, pulverize it with some type of pounding devise.(good therapy for the soul)
4. Here you can screen the dry material to remove rocks and foreign objects or rehydrate and screen the liquid slip.
5. After hours of screening and peridocially hosing off the screen to remove the tiny bits of rocks and unwanted organic stuff ....
6. The remaining goo sits for several weeks in buckets. Drain off the water that is on top as the clay settles to the bottom of the buckets.
7. Once all the water that can be siponed off is gone , pour the remaining thick soupy substance on plaster bats to dry further to a workable consistency.
8. If you can wait the clay should be aged. Plasticity in the clay over a period of time developes with more thorough "wetting of the particles". Time is required for water to permeate each individual grain. Bacterial action also assist with further development of plasticity. It needs this mellowing to ripen the clay..... which takes several weeks.
Because digging, preparing and aging Mississippi River mud is a tedious process limited number of specialtly items are created with this black gold.
Most items are related to "Old Man River". Ornamental catfish, canoes, fernleaf platters and Christmas ornaments have been a few to arise from the clay. When Mississippi River mud is fired to 1900 degrees it is a terra cota color and when fired to 2100 degrees it is a rich dark brown.
Dirt dauber nest mounted Marbles made out of local clays Ornament with lamp work bead (see the Dec. 2007 issue of Missouri Life magazine for a feature on the ornaments) 
